I personally would pick Highlander C3, if you are a DPS of course.
Highlanders get 50% more Critical damage with 2h Swords (as of iCBT2 at least.) and would have to sacrifice that to get Peltasta skills.
Also with Highlander C3 you would get you nearly 983 extra attack on the Skyliner/Crosscut combo (and that’s just for one use on each skill, keeping in mind that, Crosscut has overheat and Sky liner has 0 CD) In addition to lowering their defense with Skull Swing, and having a better Cartar Stroke/Moulinet.
It’s not much of a fight in terms of DPS. Plus the extra Crit att means less points in STR more points into DEX equaling higher evasion anyways.
Then again… it’s your character.

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